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Sumika Sumire Manga
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From Matteiru Scans:
The events of a schoolgirl's sixtieth birthday.
Kisaragi Sumi continuously took care of her grandmother, father and mother until she turned 60 years old without ever falling in love. One day after finishing her mother's funeral service, a cat calling himself Rei appeared and granted her wish to "experience her youth again". What happens when Sumi gets a second chance as a 17-year-old high-schooler once more?